Conventionally, terminal-equipped printed circuit boards are widely used as internal circuits of electrical junction boxes for vehicles. In this kind of terminal-equipped printed circuit board, lead portions provided on base end portions of board terminals are inserted into through holes of the printed circuit board and connected, by soldering, to conductive paths exposed in the through holes, whereas tab-shaped or tuning fork-shaped connection portions provided on tip end portions of the board terminals protrude on the printed circuit board, so that electrical components such as fuses and relays, connectors, and the like can be connected thereto.
Incidentally, when the lead portions of the board terminals are soldered to the conductive paths of the printed circuit board, a method is widely adopted in which intermediate sections of the board terminals in the length direction are press-fitted into and held by a resin block that is made of a synthetical resin and has leg portions as disclosed in JP 2003-217437A (JP 2003-217437A), for example, and flow or reflow soldering is performed in a state in which the board terminals are held on the printed circuit board via this leg-equipped resin block. In addition, when the printed circuit board is housed in the electrical junction box and used, the leg-equipped resin block also serves to support the insertion and removal force that occurs when a partner terminal is connected to or detached from the connection portion of a board terminal.
However, since this kind of leg-equipped resin block is formed of a synthetic resin material such as polypropylene whose linear expansion coefficient differs greatly from that of the base material of the printed circuit board, there is a problem in that when holding a board terminal using this kind of leg-equipped resin block, solder cracks tend to occur due to relative displacement between the board terminal and the printed circuit board based on the difference in linear expansion coefficients between the printed circuit board and the leg-equipped resin block, in cases such as when soldering is performed or in a state where the electrical junction box is mounted in the vehicle. Additionally, there is also an inherent problem in that the leg-equipped resin blocks have shapes that differ for each corresponding electric component or connector, and expensive molds are required for the respective shapes, and therefore an increase in costs is unavoidable.
The present disclosure has been conceived in view of the circumstances as described above, and a problem to be solved by the present disclosure is to provide an electrical junction box with a novel structure with which the occurrence of solder cracks can be advantageously avoided while achieving a reduction in manufacturing costs.